1. Field of the Invention
The present invention relates to a motorized roller such as a motor pulley or a motor roller used in a conveyor or the like, and more particularly to a motorized roller in which processing of the power transmission section thereof can be performed simply and with good productivity, and improved processing precision.
2. Description of the Related Art
Motorized rollers have been proposed in a variety of configurations. The proposed motorized roller is configured so that a motor and a reducer are disposed inside a roller body, and the rotations of the motor are reduced by the reducer and then transmitted to the roller body so that when secured to an external member the roller body is able to rotate. As shown in FIG. 5, this type of motorized roller can be used as a motor roller MR for moving a package 4 placed on top of a conveyor 2 through direct contact. Alternatively, as shown in FIG. 6, the motorized roller can also be used as a motor pulley MP for moving the package 4 via a belt 6.
As follows is a detailed description of a conventional motorized roller 10 (for example, see Japanese Patent Laid-Open Publication No. 1999-127556), based on FIG. 7. FIG. 7 shows a side sectional view of the motorized roller 10.
The motorized roller 10 comprises a roller body 12, a motor 30, and a reducer 40 as its main components.
The roller body 12 comprises a substantially circular cylindrical member, and the motor 30 and the reducer 40 are housed inside this roller body 12. Furthermore, bearings 18 and 19 are disposed at both end sections of the roller body 12, with roller covers 12a and 12b for closing these end sections disposed between the roller body and the bearings, and a pair of mounting shafts, namely a first mounting shaft 14 and a second mounting shaft 16, are retained so that they can relatively rotate with respect to the roller body 12 via the bearings 18 and 19. Accordingly, the roller body 12 can rotate about a central axis L1 of the first and second mounting shafts 14 and 16.
The first mounting shaft 14 is formed from a hollow rod-shaped member, and motor wiring 23 which is connected to the motor 30 at one end is inserted through this hollow section.
In contrast, the second mounting shaft 16 is formed from a solid rod-shaped member, and a spring casing 27 which is fixed to the roller cover 12b and provides sufficient space for housing a spring 26 is provided around the center of the roller body 12 side of the second mounting shaft 16. The spring 26 is accommodated inside this spring casing 27, and one end of the spring 26 contacts the end of the second mounting shaft 16. The other end of the spring 26 contacts a ball 29 that is held against the end of the casing 27. By employing this configuration, the compression and expansion of the spring 26 enables the second mounting shaft 16 to slide freely in and out along the central axis L1 of the roller body 12, in the direction H1 shown in the drawing.
The motor 30 is equipped with a motor shaft 32, and this motor shaft 32 also functions as the input shaft 41 for the reducer 40.
The reducer 40 is a so-called oscillating inner gearing planetary gear reducer, and comprises the input shaft 41 integrated with the motor shaft 32 of the motor 30, an eccentric body 42, an external gear 43, and an internal gear 44, and an output shaft 46 is connected to the external gear 43 via an oscillating shaft 45 that absorbs the eccentric oscillation component of the external gear 43. The output shaft 46 is also fixed to the roller body 12, thus enabling rotational driving of the roller body 12.
Next is a description of the actions of the motorized roller 10.
When the motor 30 is energized, the shaft 32 of the motor 30 rotates. The speed of this rotation of the motor shaft 32 (the input shaft 41 of the reducer 40) is reduced by the reducer 40, and the reduced output is transmitted to the roller body 12 via the output shaft 46, thereby achieving rotational driving of the roller body 12.
However, in the above roller body 12, both the end sections 12a and 12b are supported by a pair of the first mounting and second shafts 14 and 16, respectively, so as to relatively rotate, and the central region is supported by the output shaft 46 of the reducer 40 so as to integrally rotate therewith. Accordingly, in order to ensure smooth rotation of the roller body 12, each component must be processed and mounted to the roller body 12 so that the central axis of the output shaft 46, the central axis of the first mounting shaft 14, and the central axis of the second mounting shaft 16, which in combination represent the rotational axis for the roller body 12, are substantially aligned.
However, in this conventional motorized roller 10, the first and second mounting shafts 14 and 16 must be mounted to the end faces of the roller body 12, and the output shaft 46 of the reducer 40 must be attached inside the central region of the (substantially circular cylindrically shaped) roller body 12. This requires high precision processing, with the processing of the power transmission section (the section labeled Z in FIG. 7) between the roller body 12 and the output shaft 46 being particularly difficult. As a result of these processing precision difficulties, the productivity tends to fall.
In recent years, as the size of the packages being carried has increased, the demand for longer motorized rollers with greater axial length (longer roller bodies 12) has also increased, but the above processing problems are exacerbated as the length of the roller body 12 increases.